package com.yinsin.security;

import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

public class MD5 {
    // 全局数组
    private final static String[] strDigits = { "0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "a", "b", "c", "d", "e", "f" };

    private MD5() {
    }

    // 返回形式为数字跟字符串
    private static String byteToArrayString(byte bByte) {
        int iRet = bByte;
        // System.out.println("iRet="+iRet);
        if (iRet < 0) {
            iRet += 256;
        }
        int iD1 = iRet / 16;
        int iD2 = iRet % 16;
        return strDigits[iD1] + strDigits[iD2];
    }

    // 返回形式只为数字
    private static String byteToNum(byte bByte) {
        int iRet = bByte;
        System.out.println("iRet1=" + iRet);
        if (iRet < 0) {
            iRet += 256;
        }
        return String.valueOf(iRet);
    }

    // 转换字节数组为16进制字串
    private static String byteToString(byte[] bByte) {
        StringBuffer sBuffer = new StringBuffer();
        for (int i = 0; i < bByte.length; i++) {
            sBuffer.append(byteToArrayString(bByte[i]));
        }
        return sBuffer.toString();
    }

    /**
     * md5
     */
    public static String md5(String strObj) {
        String resultString = null;
        try {
            resultString = new String(strObj);
            MessageDigest md = MessageDigest.getInstance("MD5");
            // md.digest() 该函数返回值为存放哈希值结果的byte数组
            resultString = byteToString(md.digest(strObj.getBytes()));
        } catch (NoSuchAlgorithmException ex) {
            ex.printStackTrace();
        }
        return resultString;
    }
    
    public static String md5Upper(String strObj) {
        String resultString = md5(strObj);
        return resultString.toUpperCase();
    } 
    
    public static String md5For16(String strObj) {
        String resultString = md5(strObj);
        return resultString.substring(8, 24);
    }
    
    public static String md5For16Upper(String strObj) {
        String resultString = md5For16(strObj);
        return resultString.toUpperCase();
    }
    
    public static String md5For64(String strObj) {
        String md5Str = md5(strObj);
        String sha1Str = SHA1.sha1(strObj);
        return sha1Str.substring(0, 16) + md5Str + sha1Str.substring(sha1Str.length() - 16);
    }
    
    public static String md5For64Upper(String strObj) {
        String resultString = md5For64(strObj);
        return resultString.toUpperCase();
    }
    
    public static String md5b2(String strObj) {
        return md5(md5(strObj));
    }
    
    public static String md5b3(String strObj) {
        return md5(md5b2(strObj));
    }
    
    public static String md5b4(String strObj) {
        return md5(md5b3(strObj));
    }
}
